1. Field of the Invention
The present invention relates to a method of producing a tiled print product, wherein the print product is composed of a plurality of print substrates that are printed separately and are disposed adjacent to one another in at least one row. Each substrate is printed by means of a print process that creates a gloss gradient in a characteristic direction of production that is parallel to the row.
2. Description of Background Art
When a large format print product such as a billboard or the like has to be prepared, which has a width larger than the printing width of an available printer, then it is common practice to decompose the image on the print product into a number of sub-images that are printed on separate sheets. The sheets are then put together like tiles in one or more rows, so that the print product, as a whole, will show the complete image.
Depending on the print process that is used for separately printing the individual substrates or tiles, the printed images on the individual substrates may have a gloss gradient in the direction of the rows of the tiled print product. That is, the gloss of the printed image on an individual tile slightly decreases or increases in the direction in which the tiles are juxtaposed in a row. This gloss gradient is determined by a direction of production that is characteristic for the print process employed for printing the individual substrate.
For example, when the print process is a multi-pass ink jet process, wherein a printhead is scanned across the substrate in a main scanning direction that will later form the row direction of the tiled product, the characteristic direction of production will be the direction in which the printhead moves across the substrate in the first scan pass in the process of printing an individual image swath. In the second scan pass, the printhead will then move across the same swath in the opposite direction. As a consequence, at the start end of the swath, the timings at which image dots are formed in the first and second passes, respectively, are separated by a relatively large time interval, corresponding to the time that the printhead needs to move back and forth across the substrate. In contrast, at the opposite end of the swath, the image dots in the second pass will be formed immediately on the dots that have been printed in the first pass, and the interval between the two timings will be very small. These different time intervals gives rise to a slight change in the image gloss.
If one considers only the image printed on a single substrate, then the slight gradient in the image gloss is normally not perceptible to the human eye and is therefore not considered to degrade the image quality. However, when several substrates that have been printed in this way are put together, a discontinuous change in the gloss will occur at the transitions between the adjacent substrates. These discontinuous changes may be visible and may disturb the appearance of the print product as a whole.